Instant scratch-off lottery tickets are being increasingly sold by government and charitable entities around the world as sources of revenue.
Instant scratch-off lottery tickets contain hidden preprinted winning and losing game data which distinguishes this form of lottery from the various other forms in which winning numbers are drawn some time after the sale of the ticket. The growth of popularity of instant scratch-off lottery with the public is explained by the public's ability to immediately learn if the ticket is a winner or loser. The increasing popularity with the governmental and charitable entities is explained by the advantage of knowing in advance the precise number of winners and the total value of the winnings when an entire lot of tickets will have been sold.
Because of the growth in the use of instant scratch-off lottery tickets, concern has arisen as to impact of large quantities of the tickets on the environment, particularly when discarded to eventual landfill. This concern was heightened because the conventional physical structure of instant scratch-off lottery tickets includes a thin layer of aluminum foil which renders used tickets and waste that occurs during the manufacture of instant scratch-off lottery tickets non-recyclable to paper products. The aluminum foil along with certain printed and coated elements was heretofore essential in instant scratch-off lottery tickets to prevent premature disclosure of winning and losing tickets by one of several non-damaging techniques. The possibility of such premature disclosure must be prevented in order to maintain the integrity of the lottery and acceptability of the lottery ticket to the public.
Prevention of non-damaging premature disclosure of winning and losing tickets is of great importance in instant scratch-off lottery tickets because the tickets are generally sold through retail dealers who may have access to groups of tickets over periods of several days prior to sale. In such time periods it could be possible, if not prevented by technological means, that a dealer could select losers for sale to the public and winners for his own disposition. Known destructive means of premature game data disclosure do not generally threaten the integrity of instant scratch-off lottery tickets because these techniques reveal tampering and render the tickets generally unsaleable.
The conventional structure of instant scratch-off lottery tickets is based on aluminum clad cardboard. The aluminum cladding is usually of the order of 0.0003 inches in thickness adhered to cardboard stock typically of 0.010 inches in thickness. The surface of the aluminum normally must be treated to accept conventional printing inks for the decorative and thematic promotional purposes of the lottery, but also for surface compatibility with variable computer controlled printing of game data with one or more of the several available variable printing means such as digital controlled laser-xerography; digital controlled ink-jet; digital controlled light emitting diode xerography; and digital controlled ion deposition printing.
In the conventional structure, the variably printed game data is covered by one or more of coatings designed to protect the game data from premature disclosure. These coatings include a first transparent varnish overlay of the game data to provide slip for the coin or other object used to scratch off a covering opaque composite coating of filled rubber which in turn may be coated or printed with decorative and thematic patterns or images.
The normal inclusion of a layer of thin aluminum foil was intended to prevent premature reading of the game data by several principal non-destructive methods.
One non-destructive method prevented by the aluminum foil was the use of a strong light shone through the front of the ticket or as a mirror image viewed from the back of the ticket.
A second non-destructive method prevented by the foil was the delamination of the cardboard ticket by carefully separating the layer of paper first beneath the surface on which the game data is printed and then viewing the game data through this layer. By using aluminum foil as the layer on which the game data was printed such candling became impossible.
Early in the development of instant scratch-off lottery tickets the aluminum foil was believed necessary to diffuse soft X-rays. However, X-ray detection of the game data became virtually impossible due to the use of ink-jet inks of little or no detectable radio opacity. Heavy clay coatings on the cardboard surface have defeated the technique in which the top layer of paper is delaminated and the game data viewed from below. See U.S. Pat. No. 5,213,664 to Hansell. Accordingly, the need for an aluminum foil layer has been obviated by the use of low radio-opacity ink-jet type ink for the variable printing of the game data, and by the use of dense clay coatings on the surface of the cardboard base material.
The various candling techniques for non-destructive premature reading of game data have also been defeated by the use of confusion patterns preferably printed beneath thematic overprints. Confusion patterns may also be printed on the cardboard surface beneath an opaque white layer when such opaque layers are used.
However, there remains to be defeated, the non-destructive technique of causing the migration of the ink of ink-jet printed game data through various printed and coated underlayers and through a non-metal clad cardboard when the rear surface is wetted by a pad of absorbent materials such as paper toweling or paper napkin saturated with water or with water and water miscible solvents pressed against the rear side of the ticket. Variations of this basic technique include application of heated surfaces and variations in solvent constituents to a saturated paper towel or napkin to accelerate ink-jet ink migration. It has heretofore been the case that with this wet pad technique, a readable image of the game data can be transferred to the paper towel or napkin without causing residual evidence of tampering, once the lottery ticket has dried.